Hydraulic thrusting device of rolling mills

ABSTRACT

In rolling mills of the type in which the roll clearance is adjusted by hydraulic pressure, a cylindrical piece having its lower portion fixed to a hydraulic cylinder is inserted into a hollow portion formed in a roll thrusting hydraulic ram and a guide member is removably mounted in said cylindrical piece, while a detection head of a roll position detector is connected to said guide member and a detection rod which moves in said detection head and generates a position signal is disposed in said hollow portion.

United States Patent Fukui et al.

[4 1 Jan. 21, I975 HYDRAULIC THRUSTING DEVICE 0F ROLLING MILLS [75] Inventors: Kakichi Fukui; Noriyoshi Sonobe,

both of Hitachi, Japan [73] Assignee: Hitachi, Ltd., Tokyo, Japan [22] Filed: May 2, 1973 [21] Appl. No.: 356,434

[30] Foreign Application Priority Data May 17, l972 Japan 47-48112 [52] US. Cl. 72/21, 72/245 [51] Int. Cl 8211: 37/08, B21b 31/00 [58] Field of Search 72/20, 21, 28, 248

[56] References Cited UNITED STATES PATENTS 3,208.25] 9/1965 Hulls et al 72/1] 3,353,385 11/1967 Neumunn et al. M 72/21 3,516,273 6/l970 Stone 72/2] 3,546,908 12/1970 Russell v 1 M 72/21 3,757,553 9/1973 Greenherger i. 712/21 Primary Examiner-Milton S. Mehr Attorney, Agent, or FirmCraig & Antonelli [57] ABSTRACT In rolling mills of the type in which the roll clearance is adjusted by hydraulic pressure, a cylindrical piece having its lower portion fixed to a hydraulic cylinder is inserted into a hollow portion formed in a roll thrusting hydraulic ram and a guide member is removahly mounted in said cylindrical piece, while a detection head of a roll position detector is connected to said guide member and a detection rod which moves in said detection head and generates a position signal is disposed in said hollow portion,

10 Claims, 7 Drawing Figures PATENTEBJANE 1 I975 SHEET 10F 7 FIG.

PRESSURIZHJ OIL SOURCE PATENTED- 1 i 5 SHEET 2 UF 7 PATENTED W23 I975 SHEET 6 BF 7 FIG. 6

[-ATENTED 1 I975 SHEET 7 BF 7 FIG.

HYDRAULIC THRUSTING DEVICE OF ROLLING MILLS BACKGROUND OF THE INVENTION This invention relates to improvements in the hydraulic thrusting device which adjusts the roll clearance of a rolling mill by hydraulic pressure.

In recent years the demand for high accuracy in thickness of rolled products, especially cold-rolled steel strips, has been increasing. However, for controlling the plate thickness of a rolled material with high accuracy, it is necessary to adjust the roll clearance between the upper and lower work rolls in quick response to a fluctuation of the roll clearance caused by various reasons during the rolling operation. So-called thrusting devices to achieve the adjustment of roll clearance are classified into an electric type and a hydraulic type, and particularly the latter type is being used widely as it is advantageous over the former type in respect of response characteristic and thrusting efficiency. Further, the methods of detecting the position of a hydraulic ram in this type of hydraulic thrusting device include one in which the ram position is detected directly and one in which it is detected indirectly, and the use of the former method is gradually prevailing as it is superior to the latter method of respect of accuracy of detection. For instance, in U.S. Pat. No. 3,427,839 is proposed a method in which the position of the ram is detected by a differential transformer arranged on an extension of a piston rod.

The tendency to improve the accuracy of detection is particularly remarkable recently, and there have been developed simple, highly efficient digital position detectors, e.g. detectors known in tradenames of Magnescale and Inductsyn.

In such direct-detection type hydraulic thrusting devices, the position detector must be arranged adjacent the thrusting device as a matter of course. It has therefore been customary to mount the position detector on the roll housing. However, such position of the detector is undesirable because it lies in the atmosphere of lubricating oil, steam and scale and, therefore, it is quite possible that the detector undergoes the influence of heat and shocks occurring incident to the rolling operation. It is for this reason that the position detectors mentioned above which consist of an assembly of magnets made with an accuracy of the order of several microns do not operate with sufficient accuracy and much trouble is encountered in the maintenance and inspection of the detectors and in enhancing the safety of operation at the present time.

SUMMARY OF THE INVENTION The present invention has been achieved with a view in making it possible to provide such a position detector in a better atmosphere and thereby to enhance the reliability of the detector.

In order to achieve the object, according to the present invention there is provided a hydraulic thrusting device which is characterized in that a position detector is provided in the interior of a hydraulic ram. Namely, in the hydraulic thrusting device of the invention, a hollow portion is formed in the hydraulic ram, and a detection rod (movable member) and a detection head (stationary member) are disposed in said hollow portion, so that the atmosphere around the position detector is protected by the hydraulic ram and a hydraulic thrusting cylinder.

The present invention also includes in the scope thereof a hydraulic thrusting device of the construction with which the mounting and demounting of the position detector in and from and the centering and adjustment of the same relative to the position detector are facilitated. The detailed construction of the device of the invention will become apparent from the embodiments to be described hereunder:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic view of a rolling mill which is provided with the hydraulic thrusting device according to the invention;

FIGS. 2 and 3 respectively are a sectional view of the cylinder-ram assembly of an embodiment of the hydraulic thrusting device of the invention and a sectional view of the same taken on the line Ill-lll of FIG. 2;

FIGS. 4 and 5 respectively are fragmentary sectional views taken on the line IllIll of FIG. 2 and showing other embodiments of the hydraulic thrusting device of the invention; and

FIGS. 6 and 7 respectively are a sectional view of a cylinder-ram assembly of still another embodiment of the invention and a fragmentary sectional view of the same taken on the line Vll-VII of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. I shows an embodiment of the hydraulic thrusting device of the invention as applied to a four-high rolling mill having upper and lower work rolls I, 2 and upper and lower backup rolls 3, 4. A change in the clearance between the upper and lower work rolls 1, 2 is detected by a position detector 6 incorporated in a hydraulic ram 5 of the hydraulic thrusting device as a position change of the ram. Upon detecting the ram position change, the position detector 6 generates a signal which is transmitted to a controller 7. In the controller 7, the detected position signal is compared with a reference signal supplied also to the controller, and a signal representative of the deviation is generated as an outut of said controller, which is transmitted to driving means for a servo valve 8. The servo valve 8 in response to the deviation signal regulates pressurized oil being supplied from a pressurized oil source 9 to a hydraulic thrusting cylinder 10, whereby the roll clearance is adjusted quickly and accurately.

Referring to FIGS. 2 and 3, there is shown the detailed construction of the hydraulic thrusting device according to the invention. As seen, a packing II is provided on the inner wall of the hydraulic thrusting cylinder 10 and held in position by packing adapters I2, l3 against movement in a vertical direction, to prevent a leakage of oil through the gap between the ram 5 and cylinder 10. The adapter 12 is compressively retained in position by a retainer 14 and bolts 60. A cylindrical piece 15 is fixed to the bottom of the cylinder 10 by bolts 16 and an O-ring I7 is disposed between the cylindrical piece 15 and the cylinder 10 to prevent a leakage of oil from said cylinder. The hydraulic thrusting cylinder 10 is fitted in a roll housing I8 and causes the ram 5 to move up and down by pressurized oil supplied therein through a pressurized oil supply channel [9.

Within the cylindrical piece 15 are disposed a fixed detection head 20 which is a stationary member of the position detector 6, and a hollow guide member 22 for guiding a detection rod 30 which is a movable member of said position detector 6. The guide member 22 serves as a cartridge for the position detector 6 which facilitates the mounting and demounting, and the centering, of the detector, and is removably disposed in the cylindrical piece 15. The detection head is fixed in the lower end of the axial bore of the guide member 22 by a holder plate 61 and the detection rod 30 extends in the axial bore of the guide member 22 and fixed at its upper end to a holder 24 having a ball 23 in the upper end thereof. The holder 24 is disposed in a ho]- low portion 26 formed in the upper end of the hydraulic ram 5 and urged against a rocker plate 27 by a plate spring 25, and moves up and down with said ram 5. In this case, the strength of the plate spring is not so large as to push up the rocker plate 27 through the ball 23 to separate it from the ram 5. The ball 23 is provided for eliminating the influence caused by an inclination of the ram at the point of contact between it and the rocker plate 27.

According to the construction described above, it is possible to detect a vertical movement of the hydraulic ram 5 by the relative positional change in a vertical direction of the detection rod 21 and detection head 20 incorporated in said ram. Further, in the maintenance of the position detector, it is possible to take out the en tire detector 6 by removing the rocker plate 27 and pulling off the guide member 22 upwardly by grasping the holder 24 then being in an elevated position under the biasing force of the Belleville spring 25, after removing the backup roll 4. In this case, lead wires 28 connected to the detection head 20 are disconnected therefrom at a connector 29. It is also possible to carry out the centering and adjustment of the detector outside the rolling mill and put it back in the ram after such work.

The present invention may be practiced in the following mode: Namely, in the other embodiment shown in FIG. 4, a detection rod 30 and a detection sleeve 32 are disposed in the cylindrical piece 15, and the detection rod 30 is urged against the lower surface of the rocker plate 27 through a spherical surface 23 by the spring 25 for vertical movement together with the ram 5. On the other hand, the detection sleeve 32 is urged against the bottom surface of the axial bore of the cylindrical piece 15 through a retainer 33, a spring 34 and a spherical surface 35 provided at the lower end thereof. The detection rod 30 is supported in the detection sleeve 32 by bearings 36 for smooth movement therein. The detection rod 21 is connected to the lower end of the detection rod 30, while the detection head 20 is connected to the detection sleeve 32. A change in the relative position of the detection rod 30 and detection sleeve 32, that is, a positional change of the hydraulic ram 5, is detected by a change in the relative position of the detection rod 21 and detection head 20, and a signal representative of such relative positional change is transmitted to the controller through the lead wire 28.

Sealing between the ram 5 and the cylindrical piece 15 is achieved by adapters 37, 38 and a packing 39. Between the cylindrical piece l5 and the ram 5 is disposed a cartridge 40, and the gap between the cartridge 40 and the ram 5 is sealed by an O-ring 41 to prevent oil leakage. The cartridge 40 is fixed in position by an externally threaded retainer 42. The cylindrical piece 15 has a reduced diameter portion 43 so as to take a deflective force exerted thereon when the ram 5 inclinesv The construction described above will be exemplified hereinafter with concrete data: When the outer diameter of the ram Sis 710 mm, the maximum gap conccivable from the tolerances for the outer diameter of the ram and the inner diameter of the adapters l2, 13 is (1.5 mm in radial width. The maximum gap between the adapters l2, l3 and the cylinder 10 is 0.3 mm. Therefore, the total gap is 0.8 mm. On the other hand, the maximum gaps between the ram 5 and cartridge 40, between the cartridge 40 and adapters 37, 38, and between the adapters 37, 38 and cylindrical piece 15, are considered to be 0.2 mm from the normal tolerances for these elements, respectively. With the maximum gap of 0.8 mm, when the ram 5 is displaced 0.4 mm in the radial direction, the cylindrical piece 15 undergoes a lateral load through the adapters 37, 38 and deflects in an amount ofO.4 (mm) 0.2 (mm) X /2 =03 (mm). When the length I of the reduced diameter portion of the cylindrical piece 25 is 600 mm, the outer diameter D thereof is mm and the inner diameter d thereof is 65 mm. The load F acting between the adapters 37, 38 and the cylindrical piece 15 and the bending stress 8 occurring in the X portion of the cylindrical piece 15 (see FIG. 4), as calculated, are F 210 kgs and 8 3 kglmm It will, therefore, be understood that according to this embodiment it is possible, by imparting flexi bility to the cylindrical piece, to prevent an excessively large load from acting between the cylindrical piece and the adapters even when the ram is inclined or dis placed to one side within the hydraulic cylinder, and thereby to avoid deformation and wear of the cylindrical piece and adapters.

This embodiment may be modified as shown in FIG. 5. Namely, in the modification shown in FIG. 5, the cartridge 40 is extended up to the lower portion of the cylindrical piece 15 and a gap is formed extending between the ram 5 and cartridge 40 and between the cartridge 40 and cylinder 10 over a length S. When, for example, I= mm, D 102 mm, d 70 mm and S 400 mm, the load F acting between the adapters 37, 38 and cylindrical piece 15, and the bending stress 6 occurring at the X portion of the cylindrical piece 15 are respectively F 640 kgs and 8 4.54 kglmm Thus, according to this embodiment, it is also possible to pre vent deformation and wear of the cylindrical piece and adapters.

The present invention can also be practiced in the following mode so as to achieve the position detection with higher accuracy: Namely, in the embodiment of FIGS. 6 and 7, a rod 44 is disposed in the ram 5 and a piston 45 is connected to said rod 44. The pressurized oil in the hydraulic cylinder 10 is led into a pressure chamber 47 from a pressurized oil inlet channel 46 to depress the piston 45. Oil leakage from the pressure chamber 47 is prevented by packings 48, 49. The piston 45 has a rod 50 connected thereto and the detec tion rod 21 is connected to the other end of said rod 50. The gap between the cylinder 51 and rod 44 is sealed by a packing 52. The cylinder 51 is provided with oil sealing O-rings 53, 54. A lower space 55 of the cylinder 51 is communicated with the atmosphere by an outlet channel 56 so that the pressure therein will not rise above the atmospheric pressure. The cylinder 51 is positioned by a cartridge 57 and a retainer 58. The detec tion head 20 is fixed in the cartridge 57, and a change in the relative position of said detection head and detection rod 21, that is, a displacement of the ram 5 relative to the cylinder 10, is detected through the lead wire 28.

With such arrangement, since the spherical end of the rod 44 is urged against the bottom face 59 of the cylinder 10, a linear displacement of the ram 5 on the center line thereof only is detected by the detection rod 21 and detection head 20 even when said ram is dis placed radially or inclined relative to the center line of the cylinder 10, so that the position of the ram can be detected with higher accuracy than in the preceding embodiments.

According to the invention, as described hereinbefore by way of example, the position detector is disposed in the hydraulic ram. This is advantageous in that the influence of the detrimental atmosphere as mentioned previously on the detector can be minimized and the performance of the detector can be fully obtained, and is also highly advantageous in respect of maintenance and inspection of the detector and safety of operation.

What is claimed is:

1. A hydraulic thrusting device of rolling mills, comprising a cylinder-ram assembly for applying a thrust load on rolls by hydraulic pressure, an oil pressure generating source for supplying pressurized oil into the cylinder-ram assembly, means provided between the hydraulic pressure generating source and the cylinderram assembly for controlling the hydraulic pressure supplied to said cylinder-ram assembly, and a detector for detecting the roll position and for transmitting a signal to a controller of said hydraulic pressure controlling means, said detector including a stationary member and a movable member, said ram being provided with a vertically extending hollow portion, a cylindrical element having an upper and lower portion disposed in said hollow portion, the lower portion of said cylindrical element being fixed to the underside of the cylinder, the upper portion of said cylindrical element being disposed within said ram, means for sealing the upper portion of said cylindrical element within said ram, said movable member of the detector being disposed within the interior of said cylindrical piece, a rocker plate disposed on the top of said ram overlying said hollow portion, means for urging said movable member against said rocker plate, said movable member being movable within the interior of said cylindrical element and said stationary member of the detector being supported by said cylindrical element.

2. A hydraulic thrusting device of rolling mills, comprising a cylinder-ram assembly for applying a thrust load on rolls by hydraulic pressure, an oil pressure generating source for supplying pressurized oil into the cylinder-ram assembly, means provided between the hydraulic pressure generating source and the cylinderram assembly for controlling the hydraulic pressure supplied to the cylinder-ram assembly, and a detector for detecting the roll position and transmitting a signal to a controller of said hydraulic pressure controlling means, said position detector being disposed in the interior of said hydraulic ram, said ram is formed with a hollow portion and a cylindrical piece fixed to the hydraulic cylinder is inserted liquid-tightly into said hollow portion, and a guide member is removably disposed in said cylindrical piece, and further a movable member of the detector is disposed in said hollow portion and a stationary member of the same is connected to said guide member.

3. A hydraulic thrusting device of rolling mills, according to claim 2, wherein the movable member of the detector is disposed in the hollow portion of the ram, with a holder having a spherical projection connected to the upper end thereof, and said holder is urged against a rocker plate overlying the ram by a spring.

4. A hydraulic thrusting device of rolling mills, according to claim 1, wherein said cylindrical element is flexible.

5. A hydraulic thrusting device of rolling mills, according to claim 4, wherein the distance between the fixed position of said cylindrical element and the position of said sealing means is made long and the diameter of the cylindrical element is reduced over said distance.

6. A hydraulic thrusting device of rolling mills, according to claim I, wherein a cartridge fixed to the ram is interposed between said hydraulic ram and cylindrical element and sealing means are provided between said hydraulic ram and cartridge and said between said cartridge and cylindrical element.

7. A hydraulic thrusting device of rolling mills ac cording to claim 1, further comprising a guide member movably mounted within said cylindrical element, said stationary member of the position detector being connected to said guide member, and a holder means urged against said rocker plate and guided by said guide member for moving up and down with said ram, said movable member of the position detector being connected to the end of said holder means.

8. A hydraulic thrusting device of rolling mills according to claim 1, wherein said movable member of the position detector is disposed in the hollow portion of the ram, and wherein a holder means is provided having a spherical projection connected to the upper end thereof, and spring means are provided for urging said spherical projection means of said holder means against said rocker plate overlying the ram.

9. A hydraulic thrusting device of rolling mills, according to claim 1, further comprising a detection sleeve disposed in said cylindrical piece and retained in the bottom of said cylindrical piece under depressive force, said stationary member of the position detector being connected to said sleeve, a rod guided by said sleeve, said movable member of the position detector being connected to one end of said rod, and means for urging said rod and said movable member against said rocker plate.

10. A hydraulic thrusting device of rolling mills, according to claim 9, wherein said rod is provided with an upper and lower end, the upper end of said rod is re tained under depressive force in a manner to be rotatable about a point of said rocker plate and the lower end of said detection sleeve is retained under depressive force in a manner to be rotatable about a point of the bottom of said cylindrical element.

'0 i i i i 

1. A hydraulic thrusting device of rolling mills, comprising a cylinder-ram assembly for applying a thrust load on rolls by hydraulic pressure, an oil pressure generating source for supplying pressurized oil into the cylinder-ram assembly, means provided between the hydraulic pressure generating source and the cylinder-ram assembly for controlling the hydraulic pressure supplied to said cylinder-ram assembly, and a detector for detecting the roll position and for transmitting a signal to a controller of said hydraulic pressure controlling means, said detector including a stationary member and a movable member, said ram being provided with a vertically extending hollow portion, a cylindrical element having an upper and lower portion disposed in said hollow portion, the lower portion of said cylindrical element being fixed to the underside of the cylinder, the upper portion of said cylindrical element being disposed within said ram, means for sealing the upper portion of said cylindrical element within said ram, said movable member of the detector being disposed within the interior of said cylindrical piece, a rocker plate disposed on the top of said ram overlying said hollow portion, means for urging said movable member against said rocker plate, said movable member being movable within the interior of said cylindrical element and said stationary member of the detector being supported by said cylindrical element.
 2. A hydraulic thrusting device of rolling mills, comprising a cylinder-ram assembly for applying a thrust load on rolls by hydraulic pressure, an oil pressure generating source for supplying pressurized oil into the cylinder-ram assembly, means provided between the hydraulic pressure generating source and the cylinder-ram assembly for controlling the hydraulic pressure supplied to the cylinder-ram assembly, and a detector for detecting the roll position and transmitting a signal to a controller of said hydraulic pressure controlling means, said position detector being disposed in the interior of said hydraulic ram, said ram is formed with a hollow portion and a cylindrical piece fixed to the hydraulic cylinder is inserted liquid-tightly into said hollow portion, and a guide member is removably disposed in said cylindrical piece, and further a movable member of the detector is disposed in said hollow portion and a stationary member of the same is connected to said guide member.
 3. A hydraulic thrusting device of rolling mills, according to claim 2, wherein the movable member of the detector is disposed in the hollow portion of the ram, with a holder having a spherical projection connected to the upper end thereof, and said holder is urged against a rocker plate overlying the ram by a spring.
 4. A hydraulic thrusting device of rolling mills, according to claim 1, wherein said cylindrical element is flexible.
 5. A hydraulic thrusting device of rolling mills, according to claim 4, wherein the distance between the fixed position of said cylindrical element and the position of said sealing means is made long and the diameter of the cylindrical element is reduced over said distance.
 6. A hydraulic thrusting device of rolling mills, according to claim 1, wherein a cartridge fixed to the ram is interposed between said hydraulic ram and cylindrical element and sealing means are provided between said hydraulic ram and cartridge and said between said cartridge and cylindrical element.
 7. A hydraulic thrusting device of rolling mills according to claim 1, further comprising a guide member movably mounted within said cylindrical element, said stationary member of the position detector being connected to said guide member, and a holder means urged against said rocker plate and guided by said guide member for moving up and down with said ram, said movable member of the position detector being connected to the end of said holder means.
 8. A hydraulic thrusting devicE of rolling mills according to claim 1, wherein said movable member of the position detector is disposed in the hollow portion of the ram, and wherein a holder means is provided having a spherical projection connected to the upper end thereof, and spring means are provided for urging said spherical projection means of said holder means against said rocker plate overlying the ram.
 9. A hydraulic thrusting device of rolling mills, according to claim 1, further comprising a detection sleeve disposed in said cylindrical piece and retained in the bottom of said cylindrical piece under depressive force, said stationary member of the position detector being connected to said sleeve, a rod guided by said sleeve, said movable member of the position detector being connected to one end of said rod, and means for urging said rod and said movable member against said rocker plate.
 10. A hydraulic thrusting device of rolling mills, according to claim 9, wherein said rod is provided with an upper and lower end, the upper end of said rod is retained under depressive force in a manner to be rotatable about a point of said rocker plate and the lower end of said detection sleeve is retained under depressive force in a manner to be rotatable about a point of the bottom of said cylindrical element. 